Table_1_Detection of antibodies against Ornithodoros moubata salivary antigens and their association with detection of African swine fever virus in pigs slaughtered in central Uganda.docx

IntroductionAfrican swine fever (ASF) is an important disease of pigs in sub-Saharan Africa and Uganda and is threatening the pig population and agricultural economy of other continents. ASF virus (ASFV) can be transmitted from wild suids to domestic pigs through soft ticks of the Ornithodoros species. The aim of this study was to understand the relationship between domestic pigs’ O. moubata tick exposure and ASFV status.
MethodsPigs were sampled from six abattoirs in the Kampala metropolitan area of Uganda from May 2021 through June 2022. Blood, serum, and tissue samples were collected. Serum was tested for antibodies against the rtTSGP1 salivary antigens of O. moubata ticks using an indirect ELISA assay. Blood and tissue samples from pigs were tested to detect ASFV using qPCR. Probability of tick exposure was categorized based on sample-to-positive ratio cut-off points.
ResultsOut of 1,328 serum samples tested, there were 828 (62.3%) samples with a negligible probability; 369 (27.8%) with a medium probability; 90 (6.8%) with a high probability, and 41 (3.1%) with a very high probability of exposure to the O. moubata salivary antigen. There was a statistically significant association between the pigs’ O. moubata exposure and ASFV status with a higher proportion of pigs having a very high probability of infection if they were ASFV positive by blood, tonsil, and lymph nodes.
DiscussionThese results suggested that tick exposure was associated with ASFV transmission in Uganda. There were ASFV qPCR positive pigs that had no O. moubata exposure as well, which highlights that pig-to-pig and indirect contact transmission still play a significant role. This work highlights the need for further work in Uganda to investigate these transmission factors related to the O. moubata tick and ASFV transmission.

## 引言
非洲猪瘟（African swine fever, ASF）是撒哈拉以南非洲及乌干达地区猪只的重要疫病，且正威胁其他大陆的猪群与农业经济。非洲猪瘟病毒（ASF virus, ASFV）可通过钝缘蜱属（Ornithodoros）软蜱在野生猪科动物与家猪之间传播。本研究旨在阐明家猪接触摩氏钝缘蜱（Ornithodoros moubata）与非洲猪瘟病毒感染状态之间的关联。

## 材料与方法
本研究于2021年5月至2022年6月期间，在乌干达坎帕拉都会区的6家屠宰场采集猪只样本，收集血液、血清及组织样本。采用间接酶联免疫吸附试验（indirect ELISA）检测血清中针对摩氏钝缘蜱唾液抗原rtTSGP1的抗体；采用实时荧光定量聚合酶链式反应（qPCR）检测猪只血液与组织样本中的非洲猪瘟病毒。根据样本与阳性对照的比值临界值，对蜱虫接触概率进行分级。

## 结果
本次共检测1328份血清样本，其中828份（62.3%）接触摩氏钝缘蜱唾液抗原的概率可忽略，369份（27.8%）为中等接触概率，90份（6.8%）为高接触概率，41份（3.1%）为极高接触概率。家猪的摩氏钝缘蜱接触情况与非洲猪瘟病毒感染状态存在具有统计学显著性的关联：经血液、扁桃体及淋巴结检测呈非洲猪瘟病毒阳性的猪只，其感染概率为极高的占比更高。

## 讨论
本研究结果表明，在乌干达地区，蜱虫接触与非洲猪瘟病毒传播存在关联。部分经qPCR检测呈非洲猪瘟病毒阳性的猪只并未接触摩氏钝缘蜱，这凸显出猪只间直接接触与间接接触传播仍发挥着重要作用。本研究强调，乌干达地区需开展进一步研究，以探究与摩氏钝缘蜱及非洲猪瘟病毒传播相关的各类传播因素。